1use std::{env, fs};
  2use zed::{
  3    serde_json::{self, Value},
  4    settings::LspSettings,
  5};
  6use zed_extension_api::{self as zed, Result};
  7
  8const SERVER_PATH: &str = "node_modules/@elm-tooling/elm-language-server/out/node/index.js";
  9const PACKAGE_NAME: &str = "@elm-tooling/elm-language-server";
 10
 11struct ElmExtension {
 12    did_find_server: bool,
 13}
 14
 15impl ElmExtension {
 16    fn server_exists(&self) -> bool {
 17        fs::metadata(SERVER_PATH).map_or(false, |stat| stat.is_file())
 18    }
 19
 20    fn server_script_path(&mut self, server_id: &zed::LanguageServerId) -> Result<String> {
 21        let server_exists = self.server_exists();
 22        if self.did_find_server && server_exists {
 23            return Ok(SERVER_PATH.to_string());
 24        }
 25
 26        zed::set_language_server_installation_status(
 27            server_id,
 28            &zed::LanguageServerInstallationStatus::CheckingForUpdate,
 29        );
 30        let version = zed::npm_package_latest_version(PACKAGE_NAME)?;
 31
 32        if !server_exists
 33            || zed::npm_package_installed_version(PACKAGE_NAME)?.as_ref() != Some(&version)
 34        {
 35            zed::set_language_server_installation_status(
 36                server_id,
 37                &zed::LanguageServerInstallationStatus::Downloading,
 38            );
 39            let result = zed::npm_install_package(PACKAGE_NAME, &version);
 40            match result {
 41                Ok(()) => {
 42                    if !self.server_exists() {
 43                        Err(format!(
 44                            "installed package '{PACKAGE_NAME}' did not contain expected path '{SERVER_PATH}'",
 45                        ))?;
 46                    }
 47                }
 48                Err(error) => {
 49                    if !self.server_exists() {
 50                        Err(error)?;
 51                    }
 52                }
 53            }
 54        }
 55
 56        self.did_find_server = true;
 57        Ok(SERVER_PATH.to_string())
 58    }
 59}
 60
 61impl zed::Extension for ElmExtension {
 62    fn new() -> Self {
 63        Self {
 64            did_find_server: false,
 65        }
 66    }
 67
 68    fn language_server_command(
 69        &mut self,
 70        server_id: &zed::LanguageServerId,
 71        _worktree: &zed::Worktree,
 72    ) -> Result<zed::Command> {
 73        let server_path = self.server_script_path(server_id)?;
 74        Ok(zed::Command {
 75            command: zed::node_binary_path()?,
 76            args: vec![
 77                env::current_dir()
 78                    .unwrap()
 79                    .join(&server_path)
 80                    .to_string_lossy()
 81                    .to_string(),
 82                "--stdio".to_string(),
 83            ],
 84            env: Default::default(),
 85        })
 86    }
 87
 88    fn language_server_workspace_configuration(
 89        &mut self,
 90        server_id: &zed::LanguageServerId,
 91        worktree: &zed::Worktree,
 92    ) -> Result<Option<Value>> {
 93        // elm-language-server expects workspace didChangeConfiguration notification
 94        // params to be the same as lsp initialization_options
 95        let initialization_options = LspSettings::for_worktree(server_id.as_ref(), worktree)?
 96            .initialization_options
 97            .clone()
 98            .unwrap_or_default();
 99
100        Ok(Some(match initialization_options.clone().as_object_mut() {
101            Some(op) => {
102                // elm-language-server requests workspace configuration
103                // for the `elmLS` section, so we have to nest
104                // another copy of initialization_options there
105                op.insert("elmLS".into(), initialization_options);
106                serde_json::to_value(op).unwrap_or_default()
107            }
108            None => initialization_options,
109        }))
110    }
111}
112
113zed::register_extension!(ElmExtension);